Ozone generator

ABSTRACT

An ozone generator comprises an electrode located within a dielectric tube with a ground electrode formed on the outer surface of the tube. The tube and ground electrode are surrounded by a coding jacket to allow the coolant to come into contact with the ground electrode and provide efficient cooling.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application corresponds to and claims priority to CanadianApplication No. 2,291,525, filed Dec. 3, 1999. This Camnadianapplication is hereby incorporated by reference as though fully setforth herein.

BACKGROUND OF THE INVENTION

[0002] a. Field of the Invention

[0003] The present invention relates to an ozone generator.

[0004] b. Background Art

[0005] Ozone is a gas that has an aggressive oxidizing action and isused among other things to sterilize water. In this application the gasis bubbled through the water and contaminants are oxidized and may beremoved during the subsequent processing.

[0006] Ozone maybe generated by subjecting an oxygen bearing gas,typically air, to a high intensity electric field. The electric field isapplied by imposing a high frequency voltage between a pair ofelectrodes as air passes between the electrodes.

[0007] The application of the high voltage at high frequency generatessignificant heat which must be removed by cooling. In typicalinstallation the voltage is applied to an active electrode and theelectric field established between the active electrode and a groundelectrode. The electrodes face each other and the gas is passed betweenthem to generate the ozone. The ground electrode is supported on aninsulating structure which in turn is encompassed by a cooling jacket.

[0008] The application of high frequency current to the electrodeproduces significant heat which in turn must be removed efficiently bythe cooling jacket. The efficiency of the ozone generation is in part afunction of the temperature of the gas and accordingly efficient heatremoval is a prime consideration. However the support of the electrodewithin an insulating structure inhibits heat transfer from theozone-producing region and thereby limits the efficiencies that may beattained in conventional apparatus.

BRIEF SUMMARY OF THE INVENTION

[0009] It is therefore an object of the present invention to provide anozone generator in which the above disadvantages are obviated ormitigated.

[0010] In general terms the present invention provides an ozonegenerator comprising an active electrode to be connected to a powersupply, a housing encompassing said electrode to define an enclosedchamber through which gas can flow and having a wall formed from adielectric material, a ground electrode disposed on the opposite side ofsaid wall to said electrode and a coolant contacting said groundelectrode to remove heat therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] An embodiment of the invention will now be described by way ofexample only with reference to the accompanying drawings in which

[0012]FIG. 1 is a side view, partly in section of an ozone generator.

[0013]FIG. 2 is an enlarged view of a portion of the generator shown inFIG. 1.

[0014]FIG. 3 is a section on the line 3-3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Referring therefore to FIG. 1, an ozone generator generallyindicated 10 includes an outer tubular body 12 extending between a pairof T fittings 14. Each of the T fittings 14 has an end cap 16 with athrough bore 18 to receive a support tube 20. The support tube 20 isformed by a wall of a dielectric material, typically ceramics andextends through the body 12 to project beyond each of the end caps 16.The tube 20 and the body 12 in conjunction with the end caps 16 define acooling chamber 22 through which water can circulate from an inlet port24 in one branch of one of the fittings 14 to a corresponding outletport 25 on the other fitting. The tube 20 extends through a protectiveboss 26 to a second T fitting 28. The fitting 28 has a gas inlet port 30that receives a supply of oxygen gas and a sealing plate 32 in thebranch aligned with the tube 20. The sealing plate 32 supports anelectrical conductor 34 that is connected to a high voltage oscillatingpower source 36. The power source 36 is a power unit available fromPlasma Technics Inc. of Rancine, Wis. and provides a 6-kilovolt supplyat 20 kilohertz.

[0016] The conductor 34 passes through the interior of the tube 20 andis connected to an electrode 38. The electrode 38 comprises a stainlesssteel wire mesh that is supported on a cylindrical dielectric rod 40within the tube 20. The mesh 38 is wrapped about the rod 40 and providesa sliding fit within the interior of the tube 20. The interweaving ofthe mesh 38 provides voids through which the gas may pass from the inlet30 along the interior of the tube to an outlet 42 in the opposite endfitting 14.

[0017] A ground electrode 44 is formed on the outer surface of the tube20 from a conductive epoxy coating. Typically the electrode 44 is asilver filled epoxy such as that available from Chomerics Div. of ParkerHannifin Corp. of Wolburn, Me.

[0018] The ground electrode 44 is connected through cable 46 to a groundterminal 48 provided in the fitting 14.

[0019] In operation, oxygen bearing gas typically air or air enrichedwith oxygen is fed through the inlet 30 and along the interior of thetube 20 to the outlet 42. Power is supplied from the power supply 36 tothe electrode 38 to generate an alternating electric field between theelectrodes 38, 44. As the gas passes the electrode a portion of theoxygen in the gas is converted to ozone and passing through the outlet42.

[0020] The heat generated is removed by water flowing through the inlet24 and through the chamber 22 to the outlet 25. The water is in intimatecontact with the ground electrode 44 and thus provides an efficient heatremoval.

[0021] During operation, the close fit of the grid between the rod 40and the tube 20 promotes turbulence in the gas flow to facilitate theconversion process. In preliminary tests, ozone generation in the orderof 10 grams per hour has been achieved using a 6-kilovolt 20 hertzsupply. In this arrangement, the radial spacing between the support 40and tube 20 is in the order of 1.5 millimeters with a diameter of therod 40 is approximately 6 millimeters. The efficiency of the coolingprovided by the chamber 22 is such that the body 12 and fittings 14 maybe made from PVC and the fittings in contact with the ozone are madefrom kynar. However it should be noted that as the cooling and ozonegeneration functions are separated by the tube 20 the fittings on thecooling jacket may be conventional PVC fittings.

[0022] The dielectric tube 20 and rod 40 are preferably an aluminaceramic AD 998 available from Coors Ceramics Company, Golden, Colo. oran equivalent material.

[0023] Enhanced performance from the generator may be obtained byutilizing oxygen rather than air as a feed or enriching an air streamwith oxygen. An improved performance may also be attained by chillingthe coolant flow to maintain the ambient temperature of the air at a

[0024] The generators 10 may be arranged in an array with similar units,either in series flow or parallel flow, to provide the requisite massflow.

[0025] Alternative coolants may be used to water including air ifsufficient heat transfer can be attained.

1. An ozone generator comprising an active electrode to be connected toa power supply, a housing encompassing said electrode to define anenclosed chamber through which gas can flow and having a wall formedfrom a dielectric material, a ground electrode disposed on the oppositeside of said wall to said electrode and a coolant contacting said groundelectrode to remove heat therefrom.
 2. An ozone generator according toclaim 1 wherein said electrode is located on a dielectric support.
 3. Anozone generator according to claim 2 wherein said electrode extendsabout said support.
 4. An ozone generator according to claim 1 whereinsaid coolant is contained within a jacket extending over and spaced fromsaid electrode.
 5. An ozone generator according to claim 4 wherein saidhousing is tubular.
 6. An ozone generator according to claim 5 whereinsaid active electrode is tubular and is supported on a cylindrical rodwithin said housing.